I have seen this before in SQL and VB, I am now reverse engineering an Excel speadsheet and have come across the following formula:
=IF(D23<>0,\"Insufficent
Yes, it means "not equal", either less than or greater than. e.g
If x <> y Then
can be read as
if x is less than y or x is greater than y then
The logical outcome being "If x is anything except equal to y"